<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    body {
      flex-direction: column;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    #btn {
      margin: 10px;
      font-size: 32px;
    }
  </style>
</head>

<body>
  <button id="btn">屏幕录制</button>
  <video id="video" width="900" controls></video>
</body>
<script>
  const btn = document.getElementById('btn');
  const video = document.getElementById('video');
  navigator.permissions.query({name: 'camera'})
  btn.addEventListener("click", async function () {
    const stream = await navigator.mediaDevices.getDisplayMedia({ video: true });
    console.log(stream);
    video.srcObject = stream
    video.onloadedmetadata = () => video.play()
    const mime = MediaRecorder.isTypeSupported("video/webm; codecs=vp9") ? "video/webm; codecs=vp9" : "video/webm";
    const mediaRecorder = new MediaRecorder(stream, {
      mimeType: mime
    });
    //录制
    const chunks = [];
    mediaRecorder.addEventListener('dataavailable', function (e) {
      console.log(e);
      chunks.push(e.data)
    })
    //停止
    mediaRecorder.addEventListener('stop', function () {
      const blob = new Blob(chunks, { type: chunks[0].type });
      const url = URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url;
      a.download = 'video.webm';
      a.click();
    })
    //手动启动
    mediaRecorder.start()
  });




</script>

</html>